June 2011, Daily News

Early Human Ancestors Walked Fully Upright Earlier Than Scientists Thought, Study Shows

By Dan McLerran   Tue, Jul 19, 2011

How long ago did early human predecessors actually begin walking upright like us? This new study shows some surprising results.

Early Human Ancestors Walked Fully Upright Earlier Than Scientists Thought, Study Shows

Early human ancestors walked fully upright about 2 million years earlier than scientists have long suggested, according to the results of a recent study. 

A team of researchers at the University of Liverpool, along with scientists at the University of Manchester and Bournemouth University, applied a new statistical technique often used in functional brain imaging to obtain a three-dimensional average of the famous 11 footprints discovered at Laetoli, Tanzania, discovered by Mary Leakey in 1976. The footprints are interpreted to have been left originally in soft volcanic ash by a group of three individuals of the Australopithecus afarensis species following the eruption of the nearby Sadiman Volcano approximately 3.7 million years ago. Australopithecus afarensis is an early species thought to be ancestral to the Human, or Homo, evolutionary line and popularized by "Lucy", the benchmark fossilized partial skeleton discovery made in the Afar region of Ethiopia by Donald Johanson in 1974. The data was compared to other data from footprint formation and under-foot pressure studies of walking modern humans and living great apes, as well as data from computer simulations of the same taken from different reconstructed gaits of the Australopithecus afarensis species that produced the original Laetoli prints.

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A scale cast of the actual Laetoli hominid (Australopithecus afarensis) footprints, Laetoli Museum. Courtesy GIRLintheCAFE. Flickr

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What they found was eye-opening. Says Robin Crompton of Liverpool's Institute of Aging and Chronic Disease: "It was previously thought that Australopithecus afarensis walked in a crouched posture, and on the side of the foot, pushing off the ground with the middle part of the foot as today's great apes do. We found, however, that the Laetoli prints represented a type of bipedal walking that was fully upright and driven by the front of the foot, particularly the big toe, much like humans today, and quite different to bipedal walking of chimpanzees and other apes."

"The foot function represented by the prints is therefore most likely to be similar to patterns seen in modern humans. This is important because the development of the features of human foot function helped our ancestors to expand further out of Africa."

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Three dimensional scans of experimental footprints and a Laetoli footprint. A) Contour map of modern human footprint walking with a normal, extended limb gait and side view of normal, extended limb footprint. B) Contour map of modern human footprint walking with a BKBH gait and side view of BKBH print. C) Contour map of Laetoli footprint (G1-37) and side view of Laetoli footprint (G1-37). Note the difference inheel and toe depths between modern humans walking with extended and BKBH gaits. Laetoli has similar toe relative to heel depths as the modern human extended limb print. Courtesy Raichlen DA, Gordon AD, Harcourt-Smith WEH, Foster AD, Haas WR Jr (2010) Laetoli Footprints Preserve Earliest Direct Evidence of Human-Like Bipedal Biomechanics. PLoS ONE 5(3): e9769.

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These findings are significant because many scientists have long held that fully upright walking among human ancestors did not evolve until about 1.9 million years ago in the early Homo genus of species, the genus that contains the species Homo erectus. Homo erectus is the species that, based on the fossil evidence, effectively colonized the globe. According to Dr. Bill Sellers, a leading team member from the University of Manchester, "the Laetoli footprint trail is a snapshot of how early human ancestors used their feet 3.7 million years ago......we can see that the evidence points to surprisingly modern foot function very early on in the human lineage."

 

But there is a fly in the ointment. According to many paleoanthropologists (the specialists that study early human biology, culture and environment), the fully upright walking capability and longer legs helped make it possible for humans to travel longer distances and to run farther and faster than before; however, unlike Homo, Australopithecus afarensis did not sport the longer legs and shorter torso characteristic of species like Homo erectus or Homo sapiens (modern humans). Her torso was long and her legs were short, more like that of an ape, "which makes it probable," says Crompton, "that it could only walk or run effectively over short distances." 

Many scientists, including those that produced the results of a previous Liverpool study, have suggested that bipedal locomotion (upright walking) began evolving in a tree-living ancestor of both great apes and modern humans. The more recent study results appear to support the hypothesis, providing indicators that even short-legged, long-torsoed Australopithecus exhibited the locomotive capacities more akin to that of modern humans, even though they (the Australopithecines) may have been limited to shorter distances and speeds. 

Says Crompton, "we now need to determine when our ancestors first became able to walk or run over the very long distances that enabled humans to colonize the world."   

The study was funded by the Leverhulme Trust and the Natural Environment Research Council. Detailed results were published as a report in the Royal Society Journal, Interface.  

Cover Photo, Top Right: Donald Johanson pictured with cranium of Australopithecus afarensis. 

By Dan McLerran

Dan McLerran

As Founder and Editor of Popular Archaeology Magazine, Dan is a freelance writer and journalist specializing in archaeology.  He studied anthropology and archaeology in undergraduate and graduate school and has been an active participant on archaeological excavations in the U.S. and abroad.  He is the creator and administrator of Archaeological Digs, a popular weblog about archaeological excavation and field school opportunities.  

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Comments(4):

  1. Early Humans Walked Fully Upright Earlier Than Thought

    Wednesday, July 20, 2011 Alan

    'Australopithecus afarensis did not sport the longer legs and shorter torso characteristic of species like Homo erectus or Homo sapiens (modern humans). Her torso was long and her legs were short, more like that of an ape, "which makes it probable," says Crompton, "that it could only walk or run effectively over short distances."' Dan, might I suggest this anatomy differentiation is a bit of a red herring, and played far less of a role than sheer explorative inclination - the urge to go walkabout, as Aborigines might put it - which is far more closely related to creativeness/inventiveness/daring than many people realise, combined with sheer willpower and mental stamina. I don't know if you're familiar with Andrew Wyeth's 1940s' painting Christina's World, which seemingly depicts the idyllic scene of a young woman idly sitting on her hip in a field gazing at a farmhouse far off in the distance: in actual fact it's a study of a woman called Christina Olson born in the 1890s who thanks to Polio was paralysed from the waste down, yet refused to accept assistance in getting 'round, hence what we're actually seeing is her on her hip, endlessly sliding across fields and up hills to get to wherever it is she's going. I myself am a 5' 3" male with a long upper body and short legs and small feet, nor am I in any way athletic, yet whenever circumstances've required me to march enormous distances with taller people with shorter torsos, longer legs and much bigger feet, who've also been highly practised at hiking such distances, I've always been able to keep up and often outstrip these professionals simply because of my control over my mind.

  2. Problems Joining and Posting

    Wednesday, July 20, 2011 Alan

    Each time I tried to join or post, up would come a message telling me something'd gone wrong. However, whenever I merely pressed the refresh page button, up would come messages to the effect my application to join'd gone through, as'd my posting, which'd now be scrutinised for fitness, (even though the message appeared anyway!).

  3. Early Humans Walked Fully Upright Earlier Than Thought

    Friday, July 22, 2011 Paul

    Alan, Very eloquently stated. The quotations and information in the article do not reflect my own personal views......just reporting the news. Also, may I suggest that individuals like Christina Olson and you are likely more the exception than the rule........

  4. Early Humans Walked Fully Upright Earlier Than Thought

    Friday, July 22, 2011 Paul

    Alan, Very eloquently stated. The quotations and information in the article do not reflect my own personal views......just reporting the news. Also, may I suggest that individuals like Christina Olson and you are likely more the exception than the rule........